Brush holder for dynamoelectric machines



2 Sheets-$heet l AZ/FPUEfiL/A PUSEF Filed June 25, 1941 Oct. 20, 942. A E BUEROSSE BRUSH HOLDER FOR DYNAMOELECTRIC MACHINES Oct. 20, 1942. A. E. BUEROSSE I 2,299,377

BRUSH HOLDER FOR DYNAMOELECTRIC MACHINES Filed June 25, 1941 2 Sheets-Sheet 2 Patented Oct. 20, 1942 BRUSH HOLDER FOR DYNAMOELECTRIG MACHINES Alfred E. Buerosse, Wauwatosa, Wis.,

of two-thirds to George J. Buerosse,

Dam, Wis.

assignor Beaver Application June 25, 1941, Serial No. 399,585

Claims.

This invention relates to brush holders for dynamoelectric machines and is an improvement over the brush holder forming the subject matter of Patent No. 2,205,46 i, issued to G. J. Buerosse et al., June 25, 1940.

One of the most serious problems encountered in these brush holders is the maintenance of a closed seat between the brush and the commutator, regardless of change in the direction of commutator rotation. If the brush is allowed to move in its receptacle or box even a few onethousandths of an inch every time the direction of commutator rotation is reversed, the end of the brush becomes convex and will not engage the commutator with the desired surface-tosurface engagement. As a consequence, arcing takes place which soon pits the commutator.

Various schemes have been tried to eliminate the clearance or play between the brush and its receptacle which makes such objectionable shifting of the brush possible; but nothing heretofore proposed has been satisfactory. It is, therefore, a primary object of this invention to provide a brush holder so designed that there will be no play or clearance between the brush and its receptacle.

Another object of this invention resides in the provision of a brush structure of the character described which not only holds the brush firmly against rocking in its receptacle, but allows the same to be fed smoothly and freely through the receptacle and against the commutator as the end of the brush is worn away.

In this respect it is another object of this invention to provide a brush holder so designed that manual adjustment of the brush is entirely obviated and instead the brush is fed continucusly to utilize its entire useful length so that the only manual attention required is the replacement of brushes.

Another object of this invention is to provide a brush structure of the character described which is so designed that removal and replacement of the brush may be easily effected.

With the above and other objects in view which will appear as the description proceeds, this in vention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate two complete examples of the physical embodiment of the invention constructed in accordance with the best modes so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a side view of a brush holder constructed in accordance with this invention and illustrating the manner in which it is installed and used;

Figure 2 is a perspective view of the brush holder per se and showing a brush in place;

Figure 3 is a side view of the brush and. the elements which support it to more clearly show how the brush is held without play;

Figure 4 is a view similar to Figure 1 illustrating a slightly modified embodiment of the invention; and

Figure 5 is a view similar to Figure 3 but showing the disposition of the brush holding elements in that form of the invention shown in Figure 4.

Referring now particularly to the accompanying drawings in which like numerals indicate like parts, the numeral 5 designates a commutator or collector ring of a dynamoelectric machine with which one or more brushes 6 cooperate.

The olynamoelectric machine, of course, forms no part of this invention and has not been illustrated, but attention is directed to the fact that its commutator or collector ring may revolve in either direction and may reverse its direction of rotation without in anywise affecting the engagement of the brush with its peripheral surface.

Each brush may have its own holder or supporting structure indicated generally by the numeral 1 which is attached to the outer end of a supporting arm 8 adjustably mounted on a suitable part of the machine.

The holder 1 comprises a stationary head 9 clamped to a stud I 0 on the arm. Secured to the opposite faces of the head 9 and projecting therefrom are two spaced arms H. These arms are directly opposite each other and are so positioned that their longitudinal axes are tangent to a circle concentric to the axis of the commutator.

The outer ends of these arms are connected by two spaced cross pin I 2 and I3. These pins may be rollers free to revolve on their axes or they may be solid studs rigidly fastened to the arms I I. In any event the cross pins and the arms II constitute a guideway in which the brush 6 is received to be axially slidable therethrough into engagement with the commutator.

The spacing of the arms H is not material but is preferably slightly greater than the width of the brush so as to permit the brush to pass freely therebetween. The spacing of the cross pins I2 and I3, however, is important. It is greater than the thickness of the brush so that when the brush is in a position at which its longitudinal axis is normal to a plane passing through the axe of the cross pins I2 and I3, the brush may be freely passed between the cross pins without hindrance therefrom, and in fact without contacting them. This enables the brush to be readily inserted and removed.

With the brush in position, it is yieldingly urged against the commutator by a spring M, the force of which is applied to the brush in a novel manner to produce the results achieved by this invention.

As in the aforesaid Patent No. 2,205,464, the spring employed is a relatively stiff coil spring. One end of this spring is anchoredas by means of an arm 15 fixed to the head 9 while the opposite free end of the spring in tending to assume a position of axial alignment with its anchored end, presses the brush against the comutator. For this purpose, there are two curved arms I6 pivoted as at ll to the stationary head 9. The curvature of the arms enables them to reach over the stud l8 and dispose their outer free ends adjacent to the outer end of the brush.

At their outer free ends, these arms are connected by a cross pin l8 upon which a lever i9 is mounted, the free end of which is anchored to the free end of the coil spring l4 so that the tension of the spring tends to rock the connected arms H3 about their pivotal supportsin a direction toward the cross pins [2 and I3.

The space between the arms l6 accommodates the adjacent end of the brush so that said end of the brush is embraced by the arms and at this point the brush has a cross bar 28 fixed thereto, the ends of which extend out beyond the dges of the brush to be engaged by the edges of the arms. Hence, the spring pressure applied to the pivoted arms is transmitted to the brush in a direction tending to push the brush through the guideway formed primarily by the cross pins l2 and t3, and against the commutator.

The under edges of the arms l6 which engage the cross bar 2d are cut off at an angle as at 2| so that the spring force applied by the arms to the brush, in addition to exerting an endwise pressure on the brush also imparts a tuning moment thereto tending to rotate the same about either of the cross pins and into engagement with the other pin.

In this way all clearance is taken up and the brushis effectively held against rocking regardless of changes in direction of rotation of the commutator. It is to be appreciated, of course, that the spring tension is sufficiently strong to overcome the tendency to impart an opposite turning moment to the brush by the torque of the commutator during rotation thereof in a direction opposite to that indicated by the arrow in Figure 3.

This manner of taking out all play and clearance, however, does not affect the smooth feed of the brush against the comutator for although the cross pins bear tightly against the opposite faces of the brush, the vibration of the machine and the fact that the pins engage the brushes with a line contact insures the desired feed of the brush.

It is also to be observed that the brush will be fed in an exactly straight line so that the concave undersurface of the brush where it contacts the commutator will not be altered regardless of changes in direction of rotation of the commutator. The desirable surface-to-surface engagement thus will be maintained at all times.

This manner of holding the brush and feeding it further obviates all need for manual adjustment or attention, as, the spring pressure continues tofeed the brush for its entire useful length. Thereafter its removal and replacement is a simple matter as it is only necessary to lift the spring pressed arms it which exposes the brush and frees the same for ready withdrawal.

The embodiment of the invention illustrated in Figures 4 and 5 differs from that described only with regard to the specific arrangement of the connection between the spring pressed arms and the brush.

In place of the inclined edges 2| on th arms, the free ends of the arms are connected by a roller or cross pin 22 which bears directly against the end surface 23 of the brush. This end surface of the brush as best shown in Figur 5 is inclined so that the pressure of the roller or pin 22 against it imparts the desired turning moment to the brush.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent that this invention provides a substantial improvement in brush holders for dynamoelectric machines, particularly in that it assures the maintenance of the desired surfaceto-surface contact between the brush and the commutator regardless of changes in the direction of rotation of the commutator, and also in that it provides a brush holder which requires no manual attention or adjustment throughout the entire useful life of the brush, and in addition enables quick removal and replacement of the brush.

What I claim as my invention is:

1. A brush structure for dynamoelectric machines comprising: a brush having at least two opposite parallel surfaces; a stationary guideway along which the brush is slidable, said guideway having spaced parts provided with curved surfaces engageable with said opposite surfaces of the brush but spaced apart a distance greater than the thickness of the brush so that the brush is freely movable between said parts when in a position substantially normal to a plane passing through said spaced parts; a spring for feeding the brush along the guideway; and means receiving the force of the spring and applying the same to the brush, the connection between said means and the brush comprising at least one surface inclined to the axis of the brush so that the force of the spring tilts the brush about said curved surfaces to wedge the same between said spaced parts.

2. A brush structure for dynamoelectric machines comprising: a brush holder having spaced side walls connected by cross members; a brush slidable axially in said holder, the side walls of the holder being spaced apart a distance slightly in excess of the width of the brush so as to hold the brush firmly against sidewise motion but the cross members being spaced apart a distance greater than the thickness of the brush so that the brush is free to rock flatwise about either of said cross members into engagement with the other; a spring for feeding the brush continuously through the holder; and means for applying the force of the spring to the brush, the connection between said means and the brush including a surface inclined to the axis of the brush so that the force of the spring imparts a turning moment to the brush to wedge the same between said two cross members.

3. A brush structure for dynamoelectic machines comprising: a brush holder having spaced side walls connected by cross members; a brush slidable axially in said holder, the side walls of the holder being spaced apart a distance slightly in excess of the width of the brush so as to hold the brush firmly against sidewise motion but the cross members being spaced apart a distance greater than the thickness of the brush so that the brush is free to rock flatwise about either of said cross members into engagement with the other; a spring for feeding the brush continuously through the holder; and means for applying the force of the spring to the brush, the connection between said means and the brush including a surface inclined to the axis of the brush so that the force of the spring imparts a turning moment to the brush to wedge the same between said two cross members, said means being wholly separate from the brush so that it may be readily moved away from the brush to allow withdrawal and replacement of the brush.

4. A brush structure for dynamoelectric machines comprising: a brush having straight substantially parallel sides; a brush guideway comprising spaced side walls connected by two spaced cross pins, and having the brush movable axially therein, said cross pins being spaced apart a distance greater than the thickness of the brush; a pressure applicator bearing on one end of the brush for feeding the brush through the guideway; and means for translating part of the force applied to the brush by the applicator into a lateral component which rocks the brush about one cross pin into engagement with the other so as to take up play between the brush and said cross pins while feeding the brush through the guideway.

5. A brush structure for dynamoelectric ma- F:

chines comprising: a body adapted for attachment to a fixed support on the machine; spaced walls extended from said body; a pair of spaced cross members connecting the walls; a brush disposed between the walls and said cross members; a lever pivoted on the body with its free end in position to bear against one end of the brush; a spring urging the lever toward the brush; and cam means in the connection between the lever and the brush imparting a lateral force to the brush which tends to rock the same about one of the cross members into engagement with the other to thereby take up all play between the brush and said cross members.

6. A brush structure for dynamoelectric machines comprising: a body adapted for attachment to a fixed support on the machine; spaced walls extended from said body; a pair of spaced cross members connecting the walls; a brush disposed between the walls and said cross members; a lever pivoted on the body with its free end in position to bear against one end of the brush; a spring urging the lever toward the brush; and the end of the brush against which the lever bears being inclined to provide a cam surface so that the spring urged force of the lever imparts a lateral component to the brush tending to rock the same about one of the cross members into firm engagement with the other.

7. A brush structure for dynamoelectric machines comprising: a body adapted for attachment to a fixed support on the machine; spaced walls extended from said body; a pair of spaced cross members connecting the walls; a brush disposed between the walls and said cross members; a lever pivoted on the body with its free end in position to bear against one end of the brush; a spring urging the lever toward the brush; the end of the lever adjacent to the brush being inclined to provide a cam surface;

r urging said portion of the and a cross piece fixed to the brush and engaged by said cam surface so that the force applied to the brush has a lateral component at all times tending to rock the brush about one of the cross members and into firm engagement with the other.

8. A brush structure for dynamoelectric machines comprising: a body adapted for attachment to a fixed support on the machine; spaced walls extended from said body; a pair of spaced cross members connecting the walls; a brush disposed between the walls and said cross members; a pivoted lever having a portion in position to bear against one end of the brush; a spring lever toward the brush, said portion of the lever adjacent to the brush being inclined to provide a cam surface; and a cross piece fixed to the brush and engaged by said cam surface so that the force applied to the brush has a lateral component at all times tending to rock the brush about one of the cross members and into firm engagement with the other.

9. A brush structure for dynamoelectric machines comprising: a body adapted for attachment to a fixed support on the machine: spaced walls extended from said body; a pair of spaced cross members connecting the walls; a brush disposed between the walls and said cross members to be guided for axial movement thereby; a lever pivoted on the body with a part adjacent to its free end in position to bear against one end of the brush; a spring acting on the lever to cause the same to exert a force on the brush capable of moving the brush axially in one direction; and cam means in the connection between the lever and the brush imparting a lateral force to the brush for rocking the same about one of the cross members into engagement with the other to thereby take up all play between the brush and said cross members, said cam means being designed to efiect an increase in the lateral component of spring pressure on the brush upon pivotal movement of the lever in a direction to effect axial movement of the brush in response to spring pressure on the lever.

10. A brush structure for dynamoelectric machines comprising: a body adapted for attachment to a fixed support on the machine; spaced walls extended from said body; a pair of spaced cross members connecting the walls; a brush disposed between the walls and said cross members to be guided for axial movement thereby; a lever pivoted on the body with a part adjacent to its free end in position to bear against one end of the brush; a spring acting on the lever to cause the same to exert a force on the brush capable of moving the brush axially in one direction; and engaging cooperating surfaces on the brush and the lever inclined with respect to each other to form a cam connection between the lever and the brush operable to translate sprin pressure on the lever into axial and lateral components of force on the brush, said lateral component of force eifecting rocking of the brush about one of the cross members into engagement with the other of said cross members to thereby take up all play between the brush and said cross members, and pivotal motion of the lever in response to spring pressure producing axial movement of the brush and increasing the angle of cam engagement to effect an increase in the lateral component of spring pressure on the brush,

ALFRED E. BUEROSSE. 

